The preventive effects on DMH and MNNG induction of primary bowel carcinomas and on metastatic spread of grafted colon carcinomas by immunization against embryonic antigens associated with rat bowel carcinomas or reinoculation of the animal's own lymphocytes after in vitro boostering of their cytotoxic activity will be analyzed. Sequential studies are to be performed as a mean of early tumor diagnosis and to establish correlations between tumor growth in vivo and results in various in vitro assays. A RIA for antibodies to embryonic antigens will be further developed and used in sequential studies and for antigen purification and characterization.